Turbine driven locomotive



Aug. 22, 1933. LYSHOLM ET AL 1,924,062

' TURBINE DRIVEN LOCOMOTIVE Filed Nov. 26, 1932 3 Sheets-Sheet l x Q m KE I k [k I I t u l l a M 3 g 5/ 550 Aug. 22, 1933'. LYSHOLM ET AL 71,924,062

TURBINE DRIVEN LOCOMOTIVE Filed Nov. 26, 1932 3 Sheets-Sheet 2YINVENTORS Aug. 22, 1933. A. LYSHOLM El AL TURBINE DRIVEN LOCOMOTIVEFiled Nov. 26, 1952 3 Sheets-Sheet 3 law MATTORNEY 625%. 7 14 Evi II lllll Patented Aug. 22, 1933 UNITED STATES PATENT OFFICE striim and ErikOtto Eriksson,

Lidingo,

Sweden, assignors to Aktiebolaget Ljungstriims' Angturbin, CorporationStockholm, Sweden, a Swedish Application November 26, 1932, Serial No.644,474, and in Sweden January 14, 1928 8 Claims. (Cl. 105-38) 7 Thisapplication is a continuation in part replacing our copendingapplication Serial No. 333,173, filed January 17, 1929, and, as to allcommon subject matter, relates back to said application Serial No.333,173, and to foreign applications corresponding thereto for all datesand rights incident to the filing thereof.

The present invention relates to turbine driven locomotives and has forits general object the provision of a locomotive of the above typecapable of fulfilling the requirements of locomotive operation as tosize, weight, cost, tractive effort, etc., while at the same timeoperating with a high degree of economy over the range of speedsencountered in normal locomotive service. More particularly, theinvention aims to provide a turbine driven locomotive having the abovecharacteristics which is of the non-condensing type and which may be ofa size having relatively great power capacity. Still moreparticularly-the invention aims to provide a locomotive of the abovetype in which the motive fluid is supplied to the turbine at relativelyhigh pressure and temperature so that the turbine, even though operatingas a non-condensing unit, will, due to the condition of the motive fluidas delivered to the turbine and to the other characteristics inherent inthe structure when built in accordance with the invention, achieve anoperating economy comparable to-or improving upon the operating economyof condensing units for driving locomotives, as heretofore constructed,thus providing a locomotive of high operating efliciency without inimumefficiency is reached is between twenty-five to seventy-five percent ofthe maximum locomotive speed. By the term maximum speed as hereinemployed, we mean the maximum speed at which the locomotive and itspropelling mech- 3 anism are intended to operate under normal con-,

ditions, as distinguished from excess or abnormally high speeds orrunaway" speed.

Further, and in order to secure the maximum benefit from the invention,we provide a turbine locomotive including a turbine incorporated in thelocomotive in a manner providing for operation with relatively uniformhigh efliciency over a comparatively wide speed range embracing the mostfrequently employed speeds of operation of the locomotive.

Stated broadly, we provide, as a principal factor in obtaining theobjects of the invention, a

locomotive having a turbine of a type suitable for locomotive operationand incorporated in the locomotive in a manner such that thecharacteristic of the turbine known as the Parsons characteristic value(see Stodola, Steam and Gas Turbines) and hereinafter referred to as theParsons figure, is, when the turbine is operating at maximum speed,greater than 2800 (the factors determining the Parsons figure beingexpressed in metric units). Preferably, the locomotive is so designed,having regard to the number of stages and speed of operation of theturbine blading, that the sum of the squares of the speeds of theturbine blades at maximum speed is greater than 600,000 meters lsecondsWe further provide a locomotive having a boiler and a superheaterdelivering superheated steam to the turbine, which steam is preferablygenerated so as to be delivered to the, turbine at a pressure of atleast twenty atmospheres and superheated to a degree giving a totaltemperature of at least 400C.

More specifically, we prefer to employ a turbine of the combined type,that is, aturbine having both impulse and reaction blading, and toutilize the different types of blading in a manner hereinafter to bemore fully pointed out.

For a better understanding of the nature of the invention and the mannerin which it is accompanying drawings forming a part of thisspecification and the following description thereof.

Inthe drawings:

Fig.1 is a diagram illustrating performance characteristics oflocomotives having different on a larger scale, of a portion of alocomotive embodying the invention;

Fig. 0 is a diagrammatic side elevation, on a carried into effect,reference may be had to the r still larger scale, of the gearingindicated in Fi 5;

Fig. '7 is a section taken on the line 7-7 of Fig. 5; and i Fig. 8 is alongitudinal central section of a preferred form of turbine for use inthe arrangement shown in Fig. 5.

In order to facilitate an understanding of the invention, we willcompare the operating characteristics of a reciprocating enginelocomotive with apparatus in accordance with the invention.

Referring now to Fig. l, the abscissse of the co-ordinate systemrepresent speed of the locomotiveand the ordinates thereof represent theindicated power developed by the engine. Curve -A designates theindicated power of a reciprocating engine at various locomotive speeds.From zero value to the point B on the curve, which point corresponds toa certain speed B of the locomotive, the reciprocating engine operateswith constant admission or fixed point of cut-01f of steam to thecylinders and with a varying amount of steam. At speeds greater than B,steam admission per working stroke varies inversely to the speed of thelocomotive, assuming the quantity of steam to remain constant. Thereason for this is that at speeds greater than B, with a given constantquantity of steam, admission of steam to the cylinder is cut off at anearlier point in the working stroke of the piston and the steam expandsin the cylinder to a lower pressure. It is well known that decreasingthe cut-01f to the cylinder increases the indicated work done by thesteam in expanding in the cylinder. This is evidenced by the increasedarea of the indicator diagram and since the increase in work produced isobtained with a constant steam input, the efllciency pf the engine isincreased. Curve A shows that the indicated power output of thereciprocating engine, with constant steam admission, and thus theefficiency thereof, increases with the speed of the locomotive. Thegreatest efiiciency is obtained at the speed indicated at C which speedcorresponds to the maximum speed of the locomotive. i

It is, of course, possible to have a valve setting such that at lowspeeds of the locomotive, the point of cut-oil of steam admission occursso early in the working stroke of the piston that whenthe speed of thelocomotive is increased to maximum, the cut-01f is reduced to such adegree that the indicated work decreases before the maximum speedisreached. Under such conditions, the emciency of the engine is greater atlower speeds than at maximum speed. However, the last-mentionedconditions are purely theoretical and not practical. A relation such asthat above assumed between the cut-01f and the maximum speed isnotpractical because of the very large a size of the cylinders required.The size of locomotive cylinders is definitely limited because of theclearance limits imposed upon locomotives. In addition to the difilcultyof obtaining, in a locomotive, cylinders of the size required for theabove assumed conditions, increase in the size of the cylinders alsoresults in increases in mechanical losses, radiation losses, clearancelosses and leakage-losses.- These losses will be present at alllocomotive speeds and so reduce the efllciency of the engine over itsentire speed range as to preclude any gain in the'over-all efficiency ofthe engine due to adjustment of the cut-off so as to obtain maximumengine efiioiency at a speed below maximum engine speed.

Curve D designates the indicatedpower output for a turbine locomotive inaccordance with the present invention, the curve being based upon thesame initial steam pressure and temperature as for the reciprocatingengine-whose indicated output is shown by curve A. As will be observedfrom curve D, the maximum power output of the turbine is obtained atpoint E.

The curve G illustrates the indicated power output of a turbinelocomotive also constructed in accordance with the present invention,but designed to operate with a higher initial steam pressure andtemperature than thatemployed in the engine and turbine whosecharacteristics are shown by curves A and D, respectively. In thepresent instance, the maximum power output is obtained at point H. Fromcurves D and H, it will be observed that the maximum power outputs ofturbines, and thus the efficiencies thereof, are obtained, respectively,at speeds E and H, which speeds are lower than the maximum-speed C.These curves, which represent the indicated power outputs of theturbines, are plotted on the basis of the use of a constant steamquantity and therefore, are indicative of turbine efficiencies at thevarious speeds.

In stationary steam power plants where the speed of the prime mover isconstant and normal speed is the maximum speed thereof as hereinbeforedefined, the prime mover should be designed so that the greatestefliciency is theoretically obtained at its normal operating speed, thatis to say, its maximum speed. In actual practice, particularly in thecase of turbines, highest efliciency thereof is frequently obtained at aspeed somewhat above the maximum speed, be cause of the fact that toobtain a turbine which will operate with maximum theoretical efiiciencyat maximum speed involves so much additional cost, as compared with thecost of a turbine operating at somewhat lower than maximum theoreticalefliciency at its maximum speed, that the latter type of turbine iseconomically the most advantageous to employ. In locomotives, on theother hand, the operating conditions are entirely difierent, the normalaverage speed usually being considerably below the maximum speed and thenormal speed also varying over a considerable range. In accordance withthe present invention, the locomotive is designed so that maximumoperating efliciency is obtained in the range of speeds, below maximumspeed, at which the locomotive is generally operated. Experience hasshown that this range includes from between 25% to of the maximumlocomotive speed.

To obtain a locomotive turbine having characteristics of operation suchas to make it suitable for the varying conditions of load and speedimposed by locomotive operation and also having the desired propertiesfor carrying the present invention into effect, known principles ofdesign may be employed as to the details of the turbine design andwithin the scope of the inven tion the turbine may take various specificforms, the details of the turbine design being dictated to a materialdegreeby the operating characteristics desired for the specific type oflocomotive in which the turbine is incorporated.

Turbines as known today may be divided into three difierent classes,impulse turbines, reaction turbines and combined turbines, that is,turbines of the type in which both impulse blading and reaction bladingstages are employed. For reasons which are well known, r ither the pureimpulse turbine nor the pure reaction turbine is suitable as a drivingunit for locomotives, while the combined type turbine is suitable forsuch purpose since the combined turbine incorporates the characteristicsof the impulse and reaction types which are favorable with respect tolocomotive operating conditions and minimizes or eliminates thecharacteristics of impulse and reaction turbines which are not favorablewith respect to locomotive operating conditions.

A turbine of the combined type may, therefore, be used mostadvantageously in carrying our invention intoeffect. In locomotivepractice, and in order to make use of our invention, the locomotive isdesigned so that the Parsons figure of the turbine is greater than 2800when the locomotive, and consequently the turbine, is operating atmaximum speed.

The Parsons figure is well known and has been widely used for many yearsin the turbine art as a ready means of indicating turbinecharacteristics without the necessity of having to take into accountdetails of turbine design. It is in the nature of a comparator and thevalue of the figure is obtained by dividing the sum of the squares ofthe peripheral velocities of the turbine blading, or, expressed inanother way, the mean square of the peripheral velocities of the bladingtimes the number of stages, by the adiabatic heat drop in the turbine.The peripheral velocity of the turbine blading we will designate by theletter u. The adiabatic heat drop in the whole turbine is designated byA. The Parsons figure, designated by X, equals or, expressed in words,the sum of the squares of the blade speeds divided by the adiabatic heatdrop in the whole turbine. or the values of the Parsons figure as hereinemployed, u is expressed in terms of meters per second and A isexpressed in kilogram calories. It is this Parsons figure of which wemake greater than 2800, and the factor Eu which we prefer to makegreater than 600,000 meterslseconds, at maximum locomotive speed. TheParsons figure is used in connection with the present invention inpreference to speed or velocity triangles because of the fact that thisfigure is characteristic of the turbine as a whole, while velocitydiagrams are usually different for different stages in the same turbine.Thus by the use of the Parsons figure, those skilled in the art maydetermine readily the manner in which the locomotive must be designed inorder to provide the turbine characteristics ecessary in order to carrythe invention-into eff t. At the same time, the locomotive designer isnot limited in his choice of different arrangements involvingdifferences in the details of the design, of the locomotive as a wholeor of the turbine, which details may be governed by well knownprinciples of design.

In order to understand the bearing on the present invention of the valueof 2800 for the Parsons figure, reference may be had to Fig. 2 in whichare plotted the more or less diagrammatic curves K and L,-in acoordinate system in which locomotive speeds are represented byabscissa! and efliciencies of the turbine. are ordinates. The curve Kindicates the efliciency of a turbine in which allowance is not made forlosses due to impact in the blade system. The upper curve L indicatesthe efflciency of a turbine in which allowance-is made for such impactlosses. On the latter curve, the maximum efficiency of the turbineoccurs at a locomotive speed M which is substantially half of themaximum speed C. As hereinbefore mentioned, the combined type of turbineis the most suitable type for locomotive propulsion, but for differenttypes of locomotives the relation between the amount of impulse bladingandreaction blading may be different if best results are to be obtained.Generally speaking the higher the initial steam pressure, the greatershould be the percentage of the impulse blading employed, but we havefound and consider 50% impulse blading to be a maximum for satisfactoryperformance. With relatively low initial steam .pressures as little as10% impulse blading may be employed and for locomotive boiler pressuresof the order now often employed, that is to say, about 12 to 14atmospheres, 30% impulse blading represents a desirable proportion.

Considering the Parsons figure for a moment, it .can be showntheoretically that for impulse blading, maximum efiiciency will beobtained when the Parsons figure has a value of about 1800 and forreaction blading, maximum efficiency will be reached when the value ofthe Parsons figure is about 3800. Thus, for a combined type turbine inwhich the maximum amount of impulse blading is employed, maximumefliciency is to be ex-- pected when the Parsons figure has a value ofapproximately 2800 and this value therefore becomes in the nature of acritical value for the purposes of the present invention, since as thepercentage of impulse blading is decreased, the value of the Parsonsfigure at which maximum efficiency is obtained, increases.

The benefits of our invention are obtained in the manner which wecontemplate by designing the locomotive so that the Parsons figure ofthe turbine at maximum locomotive speed is greater than 2800. In orderto secure the 'maximum benefits from the invention, it is advantageousto design the locomotive so that the value of the Parsons figure atmaximum locomotive speed is materially greater than 2800, and, as willhereinafter be more fully explained, at least 4000. Thus, in the more orless diagrammatic curves which we have used for illustrative purposes inFig. 2, the Parsons figure for the turbine at maximum locomotive speed,that is, at speed C, which is not quite double the speed M, isapproximately 10,000 for a turbine the maximum efliciency of which isreached when the value of the Parsons figure is 2800, since the Parsonsfigure varies approximately as the square of the speed of the blading,due to the presence of the factor a in the formula and the fact thatmere change in speed has little effect upon the value of the factor A.

From the character of the curves indicated, it will be evident that ifthe sped is less than M, the Parsons figure for the turbine at suchlesser speed will be less than 2800 and if the speed is greater than Mthe Parsons figure for the turbine at the greater speed will be greaterthan 2800. From this it follows that if a locomotive is designed so thatat maximum speed the Parsons figure is less than 2800, the locomotivewill be working always on the descending part of the efliciency curve tothe left of M. This, obviously, will result in low average efliciency ofoperation. 0n the other hand, if the locomotive is designed so. that theParsons figure at maximum speed exceeds 2800, whenat a speed such as Mthe Parsons figure will be 2800, and the maximum efficiency of theturbine will be reached at this speed M, which may be and preferably ismaterially lower than the maximum speed of the locomotive. Thelocomotive will then operate at relatively high efliciency, due to thefact that the normal operating range of the locomotive will be betweenmaximum speed and the speed M at which maximum efiiciency occurs. Thisrange, due to the efiiciency characteristics of turbines with variationsin speed, will give a very much higher average overall efiiciency thanwill the range on a curve which reaches its maximum efliciency at themaximum speed of the locomotive.

As is well known in the art, blades for steam turbines should bedesigned in such a manner that the inlet angle of the motive fluidrelative to the blades, for the normal speed of the blades, is such thatonly minimum shock losses are in curred. In locomotive turbines, theblade speed will vary over a comparatively wide range and for thisreason it is advantageous, if the best efficiency is to be obtained, toselect a type of blade which is adapted to be used for widely varyinginlet angles of the motive fluid relative to the blading withoutincurring appreciable losses due to eddies and the like in the flow ofthe motive fluid. A blade fulfilling the above requirement for variablespeed locomotive turbines is disclosed in United States Reissue PatentNo. 18,485 granted to Alf Lysholm May 31, 1932.

The curve K in Fig. 2 is based on the use of such a blade, and from thiscurve it will be evident that-the difference in efflciency incident to'the use of this blade as compared with theefiiciency incident to the useof this blade as compared with the efiiciency obtained under theconditions represented by the curve L, in which curve allowance is madefor impact losses, will be negligible, particularly in the normaloperating speed range for the locomotive.

Where blading of this type is used, it is advantageous to use partialadmission for controlling the speed and power of the turbine.

From a comparison of curves K and L in Fig. 2, it will be observed thatwhen impact losses in a variable speed turbine are taken into account,the specific design of the turbine blade will have some influence on thespecific degree of slope or curvature of the efl'iciency curve of theturbine, but for a given type of turbine the general characteristics ofthe turbine with respect to the" speed at which maximum eflficiencyv isreached will not vary materially for a given Parsons figure, providedthat the design of the turbine is in accordance with known principles ofturbine design and that the details of the blading are worked out withnormal known factors of design in mind. It is thus evident that while,for a variable speed turbine, advantage may be derived from theemployment of a special type of blade such as that disclosed in theabove mentioned patent, the advantage so derived is'due to the fact thatthe efliciency curve produced when such a blade is employed isrelatively fiat for a greater distance on each side of the point ofmaximum efliciency than would be the case if what may be termed a normalblade profile were used in the same tur-- bine. In both cases, however,the normal characteristic of the efliciency curve of the turbine will bethe same with respect to the speed at which maximum efficiency of theturbine is reached.

We have further found that for non-condensing locomotive turbine drives,the benefits of the present invention may be enhanced if the turbine isconstructed so that the maximum eificiency of the impulse blading isreached at a different and lower locomotive speed than that at which thereaction blading reaches maximum efliciency. While at first thought, itmight appear that this relation of the locomotive speeds at whichmaximum efliciency of the two types of blades is reached follows fromthe fact that the value of the Parsons figure for maximum efficiency ofimpulse blading is lower than that for maximum efiiciency of reactionblading, such is not necessarily the case. The reason for this is thatin the case of the Parsons figure, the speed involved is peripheralvelocity and the value of this speed as modified by the adiabatic heatdrop is determinative of the value of the Parsons figure.

By relating the factors determinative of the speed of the blading sothat the impulse blading reaches maximum efficiency at a locomotivespeed lower than that at which the reaction blading reaches maximumspeed, a flatter characteristic is obtained for the efliciency curve ofthe combined turbine than would be the case if both the impulse and thereaction blading reached maximum efficiency at the same locomotivespeed, and when the value of the Parsons figure at maximum locomotivespeed is in the range contemplated by us, it will be evident that in thenormal operating speed range of the locomotive, the efficiency will notonly be high but will also vary but little as compared with thevariations in efficiency usually obtained.

In connection with the preceding discussion, it will be understood bythose skilled in the art that while for purposes of explaining thenature of the present invention we have considered impulse and reactionblading from a theoretical standpont, each being considered asconverting energy solely in accordance with its respective principle ofoperation, the practical operation of turbine blading is such that inimpulse blading some conversion of ,energy unavoidably occurs due toreaction and in reaction blading some conversion of energy unavoidablyoccurs due to impulse. For this reason there may be, as willhereinafterappear, a minor difference between the purely theoretical valuesobtainable and the results obtained in practice, but this diiference inno wise affects the general principles of the invention or the manner ofcarrying it into effect.

It will further be understood that the determination of the Parsonsfigures as herein considered is based, in accordance with usualpractice, on full steam admission and unthrottled heat drop.

Turning now more particularly to Figs. 3 and 4, we have shown alocomotive in diagrammatic fashion for illustrative purposes. Thelocomotive illustrated is of the non-condensing type and comprises aboiler 1 having a fire box 2. Reference numeral 3 indicates the usualcaband 4 the tender space for carrying fuel. Reference character 5designates the header of the usual fire tube type of superheater, thesuperheating elements connecting the inlet and discharge chambers of theheader being indicated at 6. Saturatedsteam from the boiler is suppliedto the superheater through the dry pipe '7 and superheated steam isconducted through the pipe 8 to theturbine 9. A gear boxindicatedgenerally at 10 contains a set of speedreducing gears through whichpower is transmitted to a lay shaft connected by means of connectingrods 12 (one only being shown in Fig. 3) to the driving wheels 13 of thelocomotive, the latter wheels being con nected by side rods 21 in theusual manner.

The exhaust steam from turbine 9 is conducted through the exhaust steamconduit 16 to the ex-' haust steam nozzle 14 which may be ofconventional form and which acts as a draft creating ejector bydischarging the exhaust steam upwardly through the locomotive stack 15.

If desired, some of the exhaust steam may be utilized for the purpose ofpreheating feed water and in assisting combustion. By way of example, wehave shown diagrammatically the exhaust steam branch conduit 18 leadingto the locomotive fire box and having a sub-branch 18 for conductingexhaust steam to the feed water heater indicated diagrammatically at 19.

In order to secure the best results from the present invention, it isdesirable to utilize steam generated at high pressure and superheated toa relatively high degree. We have found that if the invention 'isembodied in a locomotive adapted to supply steam to the turbine at apressure of at least 20 atmospheres and the steam is superheated to atleast 400 C. It is possible to obtain a fuel economy comparable to thatobtainable with present condensing turbine 10- comotives. We are,therefore, under these conditions, enabled to provide a locomotivegiving the economy to be expected from present condensing locomotivesbut very much lower in cost and very much more practical in operationbecause of the elimination of the necessity for a condenser. It will beunderstood, however, that the invention is not limited in itsapplication to so-called high pressure locomotives, and is alsoproductive of materially improved results in locomotives having boilersdelivering steam at relatively moderate pressures.

Turning now more particularly to Figs. 5 to 8 inclusive, we have shownby way of example a form of locomotive adapted to be operated with steamat the pressure and temperature given above and with a turbine having aParsons figure at maximum locomotive speed which is well above theminimum value of 2800, so that maximum efficiency is reached at a speedmaterially below maximum speed. For purposes of illustration we havechosen a combined type of turbine which, as hereinbefore stated, weconsider to be the most suitable type of turbine for meeting the variousdemands of locomotive service and which type of turbine we have found tobe successful in a full sized locomotive which we have constructed inaccordance with the present invention. It is to be understood, however,that the specific form of construction to be described is given merelyby way of example for illustrating what we consider to be anadvantageous form of general design? Our invention, however, is not tobe considered as in any way limited to the general type of or specificdesign herein illustrated in these figures.

Referring now more particularly to Fig. 5, the locomotive comprises aframe 25 which may be of conventional construction and which serves tosupport the boiler 26 which, in the illustrated embodiment, is of theusual fire tube locomotive type. Combustion gases from the fire box (notshown) flow through the fiues 2'! to the smoke to the admission portsofthe turbine; presently v to be described.

Turning now to the propelling mechanism for the locomotive, thiscomprises a turbine, the easing of which is indicated generally at 36,from which turbine power is transmitted through a set of speed reducinggears contained in the gear housing 37. The turbine casing and gearhousing constitute a rigid unit which may be mounted on the locomotivein any suitable manner. In the present embodiment, this unit is carriedby a forwardextension of the main frame 25 of this locomotive. Thisextensionmay, depending upon the character of the locomotive, be rigidwith frame 25 or articulated with respect thereto. Frame 25 is supportedin the usual manner upon the main driving axles of the locomotive, whichaxles carry the driving wheels 38. The forward extension of the framemay be advantageously supported by a separate axle upon which aremounted bogie wheels 39.

The driving wheels 38, of which there may be a variable number dependingupon the type of the locomotive, are connected by the usual side rods 40pivoted to wheel cranks 41. A pair of connecting rods 42 serve toconnect one pair of driving wheels 38 with the crank arms 43 on a layshaft 44 which comprises the slow speed shaft of the reduction gearingin housing 3'1.

Turning now more particularly to Figs. 6 and 7 we have shown on enlargedscale a suitable form of reduction gearing for connecting the turbinewith the lay shaft. This gearing may be constructed in accordance withdesigns known in the art.

The turbine shaft 45 (Fig. '7) is connected to and drives at shaft speedthe pinion gear 46 which, in the embodiment illustrated, is in the formof a dual gear provided withresilient teeth for reasons which willhereinafter appear. The connection between shaft 45 and pinion 46 isadvantageously through a flexible connection of known form comprisingshaft 47 extending through pinion 46, the latter being hollow.

Shafts 45 and 47 are connected by a flexible cou-.

pling indicated at 48 and shaft 47 and a suitable extension on thepinion 46 are connected by a second flexible coupling 49. Pinion 46meshes with gear 50 fixed centrally to an intermediate shaft 51, thisshaft being mounted in eccentric bearings 52 in the housing 3'7. Shaft51 has fixed thereto the gears 53 which mesh with gears 54 fixed to asecond intermediate shaft 55. Shaft 55 is suitably journalled in thegear casing 37. Intermediate the gears 54, shaft 55 has fixed theretothe gear 56 which meshes with gear 57 mounted on the lay shaft 44. Shaft44 is also suitably journalled in the housing 37 and at its outer endshas fixed thereto the crank arms 43 which are advantageously disposed sothat the crank pins carried thereby are angularly offset with respect toeach other.

In the specific form of gearing illustrated the gear 57 comprises a webportion indicated at 57a which portion is rigidly secured to shaft 44,

and a rim portion 5712 having gear'teeth thereon and adapted to havelimited turning movement peripherally with respect to the portion 57a.Force transmission through the gear is effected by a plurality of setsof springs 58 which engage both portions of the gear and which provide acertain degree of resiliency in the line of force transmission from theturbine to the lay shaft. The type of gear above described is known andneed not be described herein in further detail.

In order to reverse the direction of drive of the locomotive without aseparate reversing turbine, the intermediate shaft 51 is advantageouslymounted, as previously described, in eccentric bearings 52 which permitthis shaft to be moved from the position shown in dot -and -dash linesin Fig. 5, which position corresponds to the position shown in Fig. 6 inwhich gears 53 are in mesh with gears 54, to the position shown indotted lines in Fig. 5 in which these gears are out of mesh. A set ofreversing gears is provided, which gears are carried on an intermediateshaft 59 (see Figs. 5 and 6) these gears comprising a pair of gears 60adapted to engage gears 54 and a gear 61 adapted to mesh gear 50.

In Fig. 6, the gears are shown in mesh for forward running. For reverserunning the shaft 51 is moved out of engagement in the manner describedand in a similar manner shaft 59,. which is also mounted in eccentricjournals in the housing 37, is moved from the position shown indot-and-dash lines in Fig. 5, which position corresponds to that shownin Fig. 6, to the position shown in dotted lines in Fig. 5. With shafts51 and 59 moved to the dotted line positions indicated in Fig. 5, itwill be evident With that the line of drive from the turbine to the layshaft will include an additional set of gears which, will operate toreverse the direction of rotation of the lay shaft with respect to thedi rection of rotation of the turbine shaft.

The above described form of reversing gear is known in the art as isalso the means for eifect ing movement of the eccentric bearings tobring the desired gears into engagement. Further description thereof inthis. specification is, therefore, 'not.deemed to be necessary. It willbe evident that insofar as the present invention is concerned, aseparate reversing turbine of the usual character may be employedinstead of the reversible gearing hereinbefore described by way ofillustration. Since the use of separate reversing turbines, and variousways of effecting disconnectible driving connection between them and thegearing are known in the art, a detailed description of such anarrangement becomes unnecessary.

Turning now to Fig. 8, we have illustrated in "longitudinalcross-section a form of turbine which, when employed in a locomotivesuch as that above described, is adapted to advantageously carry thepresent invention into efiect.

This turbine is of the axial fiow combined type and comprises a rotordesignated generally at 62 the high pressure portion of the turbine andthe low pressure portion thereof is provided by the drum-like portion 71of the turbine rotor, which portion is provided with blading of thereaction type. In the form illustrated the drum carries a plurality ofrows of moving blades 72 between which rows are situated the usual rowsof stationary guide blades 73 fixed in the turbine casing. The first rowof blades on the drum portion of the rotor, indicated at 74, maybeadvantageously of the impulse type, the steam exhausted from blades 64being admitted to blades 74 through the guide nozzles 75 in the casing.

The above mentioned combined type of turbine, of which type the turbineillustrated is a typical example, is one which is known to beparticularly suitable for locomotive propulsion because of the operatingcharacteristics thereof but the specific form of the turbine may bevaried in many difierent ways within the scope of th present invention.

In order to secure the advantages of the invention, it is necessary toso relate the several factors determinative of the blade speed, havingreference to the adiabatic heat drop in the turbine, that the sum of thesquares of the blade speeds will, at maximum locomotive speed, re-

suit in a Parsons figure for the turbine greater than 2800 andpreferably, materially greater.

If we now consider the above described embodiment with reference to themanner in which the desired value of the Parsons figure is obtained wefind that the following relation of the various factors involved willgive the desired results.

Let the diameter of the driving wheels be represented by D; the diameterof the lay shaft gear 57 by Di; the diameter of the intermediate shaftgear 56 byDz; the diameter of the intermediate shaft gears 54 by Da; thediameter of the intermediate shaft gears 53 by D;; the diameter of theintermediate shaft gear 50 by D5; the diameter of the high speed pinion46 by D6, .and the mean diameter of all of the rows of moving blades inthe turbine by D, (see Fig. 8).

For the particular locomotive design of the present example, whichrepresents a locomotive suitable for passenger train service, themaximum speed of the locomotive is 112 kilometers per hour and themaximum efiiciency is at 65 percent of maximum speed, which isapproximately 73 kilometers per hour.

The diameter of the driving wheels is 1700 mm. The diameters D1, D2, D3,D4, D5 and D6 are 1000 mm. 465 mm. 1000 mm. 250 mm. 600 mm. and 150 mm.,respectively. With this diameter for the driving wheels and with thediameters given above for the several gears, the maximum locomotivespeed of 112 kin/hr corresponds to a speed of the driving wheels of 350R. P. M., while the speed of 73 km/hr, at which maximum efllciency isobtained, corresponds to a speed of 227 R. P. M. of the driving wheels.With the values given above for the diameters of the several speedreducing gears, the ratio of the speed of pinion 46 with respect to thespeed of gear 57 will be 34.4:1 and this same ratio will represent theratio of the speed of the turbine shaft 45 with respect to the speed ofrotation of the driving wheels, since pinion 46 and shaft 45 rotate atthe same speed and the driving wheels 38 rotate at the same speed asthat of the lay shaft gear 57.

With the above given dimensions, it will be found that the maximum speedof the turbine is 12,000 E. P. M. and that the speed of the turbine formaximum efiiciency is 7,800 R. P. M. These speeds are sufficiently highso that resiliency of drive through the gear train is desirable and tothis end we prefer to employ the resilient type of tooth on high speedpinion 46 in addition to the spring gear 57.

The mean diameter of the turbine blading (D7) is 355 mm. and if we takethe speed of the turbine at maximum efiiciency we find that with thismean diameter, the mean of the blade u is 145 meters/second and the meansquare of the bladespeeds is 21,000 meters /seconds I The number of rowsof moving blades, which corresponds to the number of stages in theturbine, is 20, from which it follows that Zu =420,000 meters /seconds Afair value for the exhaust pressure of a noncondensing locomotiveturbine is 1.2 atmospheres and'the adiabatic heat drop of the steam inthe turbine when it is admitted at 20 atmospheres pressure and 400 C.pressure and exhausted against a back pressure at 1.2'atmospheres is 150kilogram calories. Dividing the factor Zu by 150 we find that theParsons figure is 2800.

It will be noted that the above Parsons figure of 2800 is obtained'atthe comparatively low locomotive speed of 73 km/hr only by providing adesign in which the factor Eu is extremely high. This is provided in thepresent design by gearing the turbine to the driving wheels through athree stage reduction gearing to obtain a very high rotor speed for theturbine and further by providing a relatively large number of stages inthe'turbine, as compared with the minimum number of stages required toefiiciently extract the energy from the steam if the locomotive weredesigned solely from the standpoint of obtaininghigh maximum turbineefficiency. Obviously, the desired high value for 211. may be obtainedby designs in which the relation of the several elements determinativeof this factor vary widely, since it will be appreciated that thediameters of the driving wheels, the ratio of gear reduction, the meandiameter of the rows of turbine blading and the number of rows of theblading each contribute to the determination of the value of thisfactor.

Regardless, however, of the manner in which these individual factors ofgear diameter, gear ratio and turbine rotor diameter are varied, it willbe evident that the advantages of the present invention can be obtainedonly by the provision of a turbine and gearing arrangement which resultsin the incorporation in the locomotive of a turbine operating eitherwith extremely high rotor speed or having an abnormally large number ofstages for the given steam conditions, or both. We mention only thefactors of high rotor speed and large number of stages for obtaining thedesired high value of 211. for, while the high value of 211. which wedesire can be obtained, theoretically, with high rotor speed and a fewstages of large diameter, such an arrangement is impractical because ofthe inability of present day materials to withstand the resultingstresses imposed by centrifugal force. In order to obtain either theextreme turbine speeds or the abnormally large number of turbine stageswhich are required if a turbine locomotive embodying the presentinvention is to be constructed, advantageous factors of cost and peakefiiciency possessed by designs not incorporating the invention must besacrificed, but we have found that in the particular field to which thepresent invention relates, the adwe give in the following the principaldata with respect to a locomotive constructed in accordance with theinvention, which locomotive has been built and is at present insuccessful commercial operation. This locomotive is a freight locomotiveof relatively low speed and to enable the operators of the locomotive tocompare the performance of the locomotive with their reciprocatingengine locomotives, the turbine locomotive was constructed with a boilerdesigned to operate at the same pressure as that of their reciprocatingengine locomotives of the same class. Steam is delivered to the turbineat a pressure of about 10.5 atmospheres and at a temperature ofapproximately 400 C. The driving wheels of the locomotive are ofsomewhat smaller diameter than those given in the previously describedexample, being 1350 mm. in diameter. The total gear reduction betweenthe turbine shaft and the axles.

this ratio of reduction. The turbine is of the same 1 typeas that shownin Fig. 8.

.Because of the relatively low initial steam pressure, we extract onlyapproximately 30 percent of the total adiabatic heat drop in impulseblading, and for maximum turbine efficiency, which occurs at a turbinespeed of 8400 R. P. M. and a locomotive speed of 42 kilometers per hour,the Parsons figure is 3400, which approximates the strictly theoreticalvalue of 3200 for the Parsons figure for a turbine having 30 percentimpulse blading. The maximum turbine speed of 14000 R. P. M. correspondsto a locomotive speed of 69 km/hr and at this speed the Parsons figureof the turbine has a value of 9400.

It is to be noted that in the construction of this locomotive, themaximum efficiency is obtained at about 57 percent of maximum speed.Ordinarily a freight locomotive will operate at relatively low speeds,compared to its maximum speed, for a greater percentage of its operatingtime than will a passenger locomotive and it is therefore desirable toincrease the Parsons figure of the turbine at maximum speed to a valueresulting in maximum efliciency of operation at a speed veryconsiderably below maximum locomotive speed.

In this turbine, as well as in the turbine previously described foroperation at 20 atmospheres initial steam pressure, we provide impulseblading which operates at maximum efficiency at a lower locomotive speedthan that at which the reaction blading operates at maximum efliciency.and in the locomotive we have constructed, the impulse blading reachesmaximum efficiency at a locomotive speed of about 35 kilometers per hourwhile the reaction blading operates at highest efiiciency when thelocomotive speed is 47 kilometers per hour.

In the preferred embodiment of our invention, the locomotive speed atwhich the reaction blading reaches highest efficiency, as well as thespeed at which the highest efliciency of the turbine as a whole isreached, should be below the maximum speed of the locomotive, so thatthe largest possible part of the relatively flat efiiciency curveproduced by having the impulse vblading and the reaction blading reachpeak efficiency at difierent locomotive speeds, is brought within thenormal operating speed range of the locomotive. Inasmuch as thetheoretical value ,of the Parsons figure for reaction blading at highestefficiency is about 3800, it follows that the preferred embodiment ofourinvention comprises an arrangement in which the turbine at maximumlocomotive speed has a Parsons figure above 3800. Minor variations fromthe purely theoretical results should be allowed for, but we find thatif the value of the Parsons figure at maximum locomotive speed is madeat least 4000, the desired operating characteristics of the preferredform -will be achieved.

While in the foregoing description we have confined our consideration tolocomotives in which the turbine comprises a single unit, it will beunderstood that the inventionis not confined to this specificarrangement but may equally well be embodied in locomotives in which twoor more separate turbine rotors are employed in expanding the motivefluid down from boiler pressure to final exhaust pressure. In caseswhere a plurality of separate turbine rotors are employed, operating inseries with respect to motive fluid, the several turbine rotors are tobe considered as turbine sections and the value of the Parsons figure isto be considered with respect to the turbine as a whole, that is, all ofthe turbine sections taken together.

What we claim isz 1. A turbine driven locomotive comprising drivingwheels, a turbine having rotatable blade carrying means, blades on saidmeans, reduction gearing for causing said means to drive said wheels,the ratio of speed reduction of said gearing being so related to thediameter of said driving wheels that the speed of rotation of said meansat which maximum turbine efiiciency is produced corresponds to alocomotive speed less than the maximum speed thereof, and the diameterof said means, the number of rows of moving blades, and the speed ofrotation of said means as determined by the diameter of said driving.wheels and the ratio of said gearing being so related to the differencein heat content of the motive fluid as admitted to and as exhausted fromthe turbine that at speeds within normal operation the ratio between thesum of the squares of the values of the blade speeds, expressed inmeters per second, and the adiabatic heat drop of the motive fluid-inthe turbine, expressed in kilogram calories, is greater than 2800:1.

2. A turbine driven locomotive comprising driving wheels, a turbinehaving rotatable blade carrying means, rows ofjblades on said means,reduction gearing for causing said means to drive said wheels, the ratioof speed reduction of said gearing being sorelated to the diameter ofsaid driving wheels that the speed of rotation of said means at whichmaximum turbine efficiency is produced corresponds to a locomotive speedbetween 25 and 75 percent of the maximum speed thereof, and the diameterof said means, the number of rows of moving blades, and the speed ofrotation of said means as determined by the diameter of said drivingwheels and the ratio of said gearing being so related to the differencein heat content of the motive fluid as admitted to and as exhausted fromthe turbine that'the ratio between the sum of the squares of the valuesof the blade speeds at maximum speed, expressed in meters per second,and the adiabatic heat drop of the motive fluid in the turbine,expressed in kilogram calories, is great er than 2800:1.

3. A turbine driven locomotive comprising driving wheels, a turbinehaving rotatable blade carrying means, rows of blades on said means,reduction gearing for causing said means to drive said wheels, the ratioof speed reduction of said gearing being so related to the diameter ofsaid driving wheels that the speed of rotation of said means at whichmaximum turbine efiiciency is produced corresponds to a locomotivespeed-less than the maximum speed thereof; and the diameter of saidmeans, the number of rows of moving blades, and the speed of rotation ofsaid means as determined by the diameter of said driving wheels and theratio of said gearing being so related to the difierence in heat contentof the motive fluid as admitted to and as exhausted from the turbinethat the ratio between the sum of the squares of the values of the bladespeeds at maximum speed, expressed in meters per second, and theadiabatic heat drop of the motive fluid in the turbine, expressed inkilogram calories, is greater than 2800:l, said sum of the squares ofthe blade speeds being greater than 600,000 meters /second 4. A turbinedriven locomotive comprising a boiler, a superheater, driving wheels, a.non-' condensing turbine having rotatable blade carrying means, bladeson said means, reduction gearing for causing said ,means to drive saidwheels, the ratio of speed reduction of said gearing being so related tothe diameter of said driving wheels that the speed of rotation of saidmeans at which maximum turbine efliciency is produced corresponds to alocomotive speed less than the maximum speed thereof, and the di-'ameter of said means, the number of blades and the speed of rotation ofsaid means as determined by the diameter of said driving wheels and theratio of said gearing being so related to the difierence'in' heatcontent of the motive fluid as admitted to and as exhausted from theturbine that the ratio between the sum of the squares of the values ofthe blade speeds at maximum speed,- expr'es'sed in meters per second,and the adiabatic heat drop of the motive fluid in the turbine,expressed in kilogram calories, is greater than 2800:l, said boiler andsaid superheater supplying steam to said turbine at a temperature of atleast 400 C.

5. A turbine driven locomotive comprising a boiler, a superheater,driving wheels, 8. nonto steam flow through the means as determined bythe diameter of said driving wheels and the ratio of said gearing beingso related to the difference in heat content of the motive fluid asadmitted to and as exhausted from the turbine that the ratio-lbetweenthe sum of the squares of the values of the blade speeds at maximumspeed, expressed in meters per second, and the adiabatic heat drop ofthe motive fiuid in the turbine, expressed in kilogram calories isgreater than 280: 1, said boiler and superheater supplying steam to saidturbine at a pressure of at least 20 atmospheres and a temperature of atleast 400 C.

6. A turbine driven locomotive comprising a boiler, driving wheels, aturbine having rotatable blade-carrying means, rows of blades on saidmeans comprising impulse blades and reaction blades arranged in theorder named with respect turbine, the amount of with respect to theamount of reaction blading being such that the adiabatic heat drop inthe impulse blading does not exceed one half of the total availableadiabatic heat drop, and reduction gearing for causing said means todrive said wheels, the ratio of speed reduction of said gearing withrespect to the impulse blading as compared with the reaction blading andthe diameters and numbers 0! rows of the difierent types of bladingbeing related so that the speed of the locomotive at which the impulseblading operates at maximum efiiciency is different from the speed ofthe locomotive at which the reaction blading operates at maximumefiiciency.

'7. A turbine driven locomotive comprising a boiler, a superheater,driving wheels, 9. non-condensing turbine having rotatable.blade-carrying blades on said means comprising impulse blades andreaction blades arranged in the order named with respect to steam flowthrough the turbine, means for supplying superheated steam to theimpulse blading from the superheater, means for exhausting steam fromthe reaction blading to the atmosphere, the amount of impulse bladingwith respect to the amount of reaction blading being such that theadiabatic heat drop in the impulse blading does not exceed one half ofthe total available adiabatimpulse blading heated steam to ie heat drop,and reduction gearing for causing said means to drive said wheels,reduction of said gearing with respect to the imZ- pulse blading ascompared with the reaction blading and the diameters and numbers of rowsof the difierent types of blading being related so: that the speed ofthe locomotive at which the impulse blading operates at maximumefflciency is lower than the speed of the locomotive at which thereaction blading operates at maximum efliciency.

8. A turbine drivenlocomotive comprising a boiler, a superheater,driving wheels, a non-condensing turbine having rotatable blade carryingmeans, rows of blades on said means comprising impulse blades andreaction blades arranged in the order vnamed with respect to steam flowthough the turbine, means for supplying superthe impulse blading fromthe superheater, means for exhausting steam from the reaction blading tothe atmosphere, the amount of impulse blading with respect to the amountof reaction blading being such that the adiabatic heat drop in theimpulse blading does not exceed one half of the total availableadiabatic heat drop, and reduction gearing for causing said means todrive said wheels, the ratio of speed reduct'on of said gearing withrespect to the impulse blading as compared with the reaction blading andthe diameters and numbers of the ratio of speed i rows of the differenttypes of blading being related so that the speed of the locomotive atwhich the impulse blading operates at maximum emciency is lower than thespeed of the locomotive at which the reaction blading operates atmaximum efllciency and the diameters of the driving wheels, the ratio ofspeed reduction of the gearing and the diameters and numbers of rows ofblades of the whole turbine being related to the'total availableadiabatic heat dropso that at maximum speed of operation of thelocomotive, the Parsons figure for the whole turbine is at least 4000,expressed in metric units.

-ALF LYsHoLM.

FnEDRrK LJUNGSTRDM. nam'o'rro ERIKSSON.

CERTIFICATE OF CORRECTION.

Patent No. l, 924, 062.

August 22, 1933.

ALF LYSHOLM, ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction "as compared with 25,for "It" read and that the said strike out the words this blade"; page5, line "280; 1" read "2800:1";

as follows: I Page 4, lines 36 and37, the efficiency incident to the useof "it"; page 9, line 10, claim 5, for Letters Patent should be readwith,

these corrections there in that the same may conform to the record ofthe .case

in the Patent 0iiice. Signed and sealed Q (Seall' this 26th day ofSeptember, A. D. 1933.

l". M. Hopkins Acting Commissioner of Patents.

